Laser light transmitting colored polyolefin resin compositions and process for laser welding

ABSTRACT

Laser ray transmitting colored polyolefin resin composition containing an anthraquinone salt forming dye below; and method of laser welding wherein welding a portion of contact of a laser ray transmitting material of said resin composition and a laser ray absorbing material by irradiating laser ray so that the laser ray transmits the laser ray transmitting material and is absorbed in the laser ray absorbing material with the laser ray transmitting material and the laser ray absorbing material in contact with each other:  
                 
 
A, B: —NH— or —O—; R 1 —R 3 : hydrogen, amino, hydroxy, halogen; R 4 —R 13 : hydrogen, alkyl, nitro, sulfonic group; Ki n+ : organic ammonium ion; m: 1 or 2; n: 1 or 2; the sulfonic group is —SO 3  or SO 3 M, the number of —SO 3  being m, M representing hydrogen or an alkali metal.

FIELD OF THE INVENTION

The present invention relates to a laser ray transmitting coloredpolyolefin resin composition containing an anthraquinone salt formingdye and a method of laser welding using the laser ray transmittingcolored polyolefin resin composition.

BACKGROUND ART

Laser welding of synthetic resin materials can, for example, beconducted as described below. As shown in FIG. 1, one part incorporatinga laser ray transmitting material and another part incorporating a laserray absorbing material are brought into contact with each other. Whenirradiating laser ray from the laser ray transmitting material side tothe laser ray absorbing material, the laser ray that has transmitted thelaser ray transmitting material is absorbed in the laser ray absorbingmaterial and generates heat. By this heat, the laser ray absorbingmaterial is molten around the portion that has absorbed the laser ray,and the laser ray transmitting material is also molten, the resins ofthe two parts fuse together, and upon cooling sufficient weldingstrength is obtained and the laser ray transmitting material and thelaser ray absorbing material are joined firmly. Features of laserwelding include the capability of welding without bringing the laser raygeneration portion in contact with the portion to be welded, the minimalthermal effect on the surrounding portion because the heating islocalized, freedom from the problem of mechanical vibration, thecapability of welding of fine portions and structures, highreproducibility, maintenance of high air-tightness, high weldingstrength, inconspicuous welded portion, and no generation of dust etc.

Traditionally, resin parts have been joined together by clamping withclamping parts (bolts, screws, clips, etc.), adhesion using adhesives,vibration welding, ultrasonic welding, etc. According to laser welding,labor saving, productivity improvements, production cost reductions,etc. can be achieved because secure welding is achieved by simpleoperation to provide strength equivalent to or more than the levelsexpected by conventional method and in addition vibration and heat haveminimal effects. With these features, laser welding is suitable for thejoining of functional components, electronic components, etc., for whichthe avoidance of the influence of vibration or heat is desired in, forexample, automobile industry, electric/electronic industry and otherfields, and is applicable to the joining of resin parts of complexshapes.

As a technology concerning laser welding, Japanese Patent Laid-Open No.HEI-11-170371 describes a method of laser welding comprising a processwherein laser ray is irradiated so that it focuses on a portion where anopaque part comprising a laser ray absorbing thermoplastic syntheticresin and a colorless transparent part comprising a laser raytransmitting thermoplastic synthetic resin are in contact with eachother. In this case, however, when viewed from the colorless transparentpart side, the welded portion differs from the non-welded portion incolor and smoothness, posing a problem of poor appearance.

Additionally, WO02/36329 describes laser welding of a polyolefin resinusing an anthraquinone dye and a perinone dye as colorants. However, ifa common neutral dye is used to color a polyolefin resin, the dye isunlikely to fix due to the weak binding of polyolefin resins to dyes andin addition because the neutral dye used is very highly soluble inresins, posing a problem of the bleeding phenomenon, in which the dyemigrates elsewhere in the event of contact with another polyolefinresin. This has been a critical problem not only in the use of laserwelding, but also in general situations of coloring polyolefin resins.

The present invention has been developed in view of the aforementionedproblems in the prior art, and is intended to provide a laser raytransmitting colored polyolefin resin composition that is highlytransmittable for laser ray wavelength band (wavelengths from 800 nm to1200 nm, e.g., 808, 820, 840, 940, and 1064 nm), that undergoes no colorfading of the colored polyolefin resin part in the heat treatmentprocess prior to laser welding of the resin part, that permits laserwelding with substantially no sublimation of dye, and that possessessufficient anti-bleeding quality, and a method of laser welding usingthe same laser ray transmitting colored polyolefin resin composition.

DISCLOSURE OF THE INVENTION

The laser ray transmitting colored polyolefin resin composition of thepresent invention contains an anthraquinone salt forming dye (i.e., asalt forming dye composed of an anionic component which is obtainablefrom an anthraquinone acid dye and an organic ammonium component)represented by Formula (1) below:

in Formula (1),

-   each of A and B independently represents —NH— or —O—,-   each of R¹ to R³ independently represents hydrogen, an amino group,    a hydroxy group or a halogen,-   each of R⁴ to R¹³ independently represents hydrogen, an alkyl group,    a nitro group or a sulfonic group,-   Ki^(n+) represents an organic ammonium ion,-   m represents 1 or 2, and-   n represents 1 or 2;-   the sulfonic group is —SO₃ or SO₃M, the number of —SO₃ being m, M    representing hydrogen or an alkali metal, and each of M may be    identical or not provided that the number of SO₃M is 2 or more.

An anthraquinone salt forming dye represented by Formula (1) above fixesstably in polyolefin resins, in which dyes are unlikely to fix due toweak binding to dyes, and is well compatible with resins. Therefore, bycoloring with this anthraquinone salt forming dye, it is possible toobtain a laser ray transmitting polyolefin resin part that is stable toheat, that is unsusceptible to environment, and that possesses excellentlaser transmission.

A big feature of the above-described anthraquinone salt forming dyeresides in that two of the following structure are present in theanthraquinone structure.

It is also important that the number of sulfonic groups in theanthraquinone salt forming dye should be adjusted.

The laser ray transmitting colored polyolefin resin composition of thepresent invention well transmits ray in the wavelength range from about800 nm by semiconductor laser to about 1100 nm by YAG laser, i.e. laserray, exhibits high fastness such as to heat and light, has a goodanti-migration property, chemical resistance, etc., and exhibits abrilliant color. The colored resin part with this laser ray transmittingcolored polyolefin resin composition permits laser welding withoutfading of the color of the resin part in the heat treatment processprior to laser welding, with substantially no dye sublimation. The laserray transmitting colored polyolefin resin composition of the presentinvention colored using a master batch is more uniformly colored, doesnot exhibit light scattering due to the colorant, and exhibits goodlaser transmission.

Meantime, the method of laser welding of the present invention compriseswelding a contact portion of a laser ray transmitting materialcomprising any of the aforementioned laser ray transmitting coloredpolyolefin resins and a laser ray absorbing material by irradiatinglaser ray so that the laser transmits the laser ray transmittingmaterial and is absorbed in the laser ray absorbing material with thelaser ray transmitting material and the laser ray absorbing material incontact with each other.

According to the method of laser welding of the present invention, aportion of contact of a laser ray transmitting material and a laser rayabsorbing material can be welded by irradiating laser ray so that thelaser transmits the laser ray transmitting material and is absorbed inthe laser ray absorbing material with the laser ray transmittingmaterial and the laser ray absorbing material in contact with eachother. The laser ray transmitting material in this method of laserwelding permits laser welding without fading of the color of the resinpart in the heat treatment process prior to laser welding, withsubstantially no dye sublimation.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a lateral view of the laser welding test.

FIG. 2 is an oblique view of the laser welding test.

MODE FOR EMBODYING THE INVENTION

The laser ray transmitting colored polyolefin resin composition of thepresent invention contains at least an anthraquinone salt forming dyerepresented by Formula (1) above. Because this anthraquinone saltforming dye has a large molecular weight and is highly bindable topolyolefin resins, particularly polypropylene resins, it actseffectively on heat resistance and anti-sublimation quality in the laserray transmitting colored polyolefin resin composition of the presentinvention.

The polyolefin resin used in the present invention is not subject tolimitation.

As examples thereof, there may be mentioned homopolymers of α-olefinssuch as ethylene, propylene, butene-1, 3-methylbutene-1,4-methylpentene-1 and octene-1 or copolymers thereof, or copolymers (ascopolymers, there may be mentioned block copolymers, random copolymers,and graft copolymers) of these and other copolymerizable unsaturatedmonomers.

Specifically, there may be mentioned polyethylene resins such ashigh-density polyethylene, intermediate-density polyethylene,low-density polyethylene, linear low-density polyethylene,ethylene-vinyl acetate copolymer and ethylene-ethyl acrylate copolymer;polypropylene resins such as propylene homopolymers, propylene-ethyleneblock copolymers or random copolymers and propylene-ethylene-butene-1copolymers; polybutene-1, poly-4-methylpentene-1, etc.

These polyolefin resins may be used singly or in combination of two ormore species. As other examples of polyolefin resins in the presentinvention, there may be mentioned polyolefin elastomers such aspolypropylene resin elastomers, various thermoplastic elastomers(including various rubbers) containing the above-described resins asmain component, polyolefin resins containing synthetic waxes or naturalwaxes, and the like.

In the present invention, it is preferable that, of these, apolypropylene resin and/or a polyethylene resin be used. A polypropyleneresin is particularly preferred. This polypropylene resin is not subjectto limitation and can be used over a broad range of molecular weight.

As a polyolefin resin, there may be used an acid-modified polyolefinmodified with an unsaturated carboxylic acid or a derivative thereof,foaming polypropylene containing a foaming agent added to the resinwithout affecting the desired effect, and the like.

As propylene copolymers like as described above, those containingpropylene at 75% by weight or more, particularly at 90% by weight ormore, are preferred because they retain the crystallinity, rigidity,chemical resistance, etc. that characterize polypropylene resins.

As specific examples of the aforementioned copolymerizable monomer,there may be mentioned one species or two or more species of

-   α-olefins having 2 or 4 to 12 carbon atoms, such as ethylene,    1-butene, isobutene, pentene-1, 3-methyl-butene-1, hexene-1,    4-methyl-pentene-1, 3,4-dimethyl-butene-1, heptene-1,    3-methyl-hexene-1, octene-1, and decene-1;-   cycloolefins such as cyclopentene, norbornane, and    1,4,5,8-dimethano-1,2,3,4,4a,8,8a-6-octahydronaphthalene;-   dienes such as 5-methylene-2-norbornane, 5-ethylidene-2-norbornane,    1,4-hexadiene, methyl-1,4-hexadiene, and 7-methyl-1,6-octadiene;-   vinyl monomers such as vinyl chloride, vinylidene chloride,    acrylonitrile, vinyl acetate, acrylic acid, methacrylic acid, butyl    acrylate, methyl methacrylate, and maleic anhydride; and the like.

An anthraquinone salt forming dye in the present invention can beobtained by a salt-forming reaction of an anion from an anthraquinoneacid dye and an organic ammonium ion (e.g., cations from primary amine,secondary amine, tertiary amine, guanidines, or rosin amines, etc.).This salt-forming reaction may employ a commonly known ionic reaction.For example, an acid dye component having two sulfonic groups isdispersed in water, an organic amine component in a ratio of 1.5 to 2.3mols per mol of the dye is dissolved in aqueous hydrochloric acid; thissolution is added drop by drop to the dispersion liquid, and thereaction is carried out with stirring for several hours. By filteringthis reaction mixture, washing the cake filtered out with water, anddrying it, an anthraquinone salt forming dye of the present inventioncan be obtained.

With respect to Formula (1) above, which represents an anthraquinonesalt forming dye in the present invention, A, B and R¹ to R¹³ representthe following groups or atoms, respectively.

Each of A and B independently represents —NH— or —O—.

Each of R¹ to R³ independently represents hydrogen, an amino group, ahydroxy group or a halogen (e.g., Cl, Br).

Each of R⁴ to R¹³ independently represents hydrogen, an alkyl group(e.g., alkyl groups having 1 to 8 carbon atoms, such as methyl, ethyl,propyl, isopropyl, n-butyl, tert-butyl, n-pentyl, isopentyl, hexyl,heptyl and octyl), a nitro group or a sulfonic group.

Ki^(n+) represents an organic ammonium ion; m represents 1 or 2, and nrepresents 1 or 2.

Referring to the laser ray transmitting colored polyolefin resincomposition of the present invention, it is preferable that in Formula(1) above, at least one of R⁴ to R⁸ be a sulfonic group, and also atleast one of R⁹ to R¹³ be a sulfonic group.

As specific examples of the anthraquinone acid dye corresponding to 5the anionic component of the anthraquinone salt forming dye in thepresent invention, the following examples may be mentioned. However, thepresent invention is not limited to these examples.

Example Compound (1)-1

Example Compound (1)-2

Example Compound (1)-3

Example Compound (1)-4

Example Compound (1)-5

In Formula (1) above, Ki^(n+) is an organic ammonium ion thatconstitutes the organic ammonium component of an anthraquinone saltforming dye in the present invention, and may be one represented byFormula (2) or (3) below.

In Formula (2) above, each of R¹⁴ through R¹⁷ independently represents,hydrogen,

-   an alkyl group (e.g., alkyl groups having 1 to 12 carbon atoms that    may be branched, such as methyl, ethyl, n-propyl, isopropyl,    n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, tert-pentyl,    hexyl, heptyl, octyl, nonyl, decyl, undecyl and dodecyl),-   a cycloalkyl group (e.g., cycloalkyl groups having 3 to 8 carbon    atoms, such as cyclopropyl, cyclopentyl, cyclohexyl and cycloheptyl,    or dihydroaziethylamine residues),-   an alkoxyalkyl group (e.g., alkoxyalkyl groups having 2 to 20 carbon    atoms, such as [methoxy, ethoxy, propoxy, butoxy, pentyloxy,    hexyloxy, or octyloxy, etc.]-[methyl, ethyl, propyl, butyl, pentyl,    or octyl, etc.] etc., i.e., ethoxymethyl, methoxyethyl, etc.),-   an alkanol group (e.g. —CH₂OH, —C₂H₄OH, —C₃H₆OH, etc.),-   an aryl group (e.g., phenyl, lower-alkyl-substituted phenyls,    halogenated phenyls, naphthyl, aminonaphthyls) having or not having    a substituent [e.g., amino groups, lower (1 to 4 carbon atoms) alkyl    groups, halogens such as Cl and Br],-   an aralkyl group (e.g., benzyl group, α-methylbenzyl group,    α,α-dimethylbenzyl group, α-butylbenzyl group, phenethyl group,    naphthylalkyl groups [e.g., naphthylmethyl, naphthylethyl, etc.])    having or not having a substituent [e.g., amino groups, alkyl groups    having 1 to 4 carbon atoms, halogens such as Cl and Br], or-   a group represented by Formula (C) below.

In Formula (3) above, each of R¹⁸ to R²¹ independently representshydrogen or an aryl group (e.g., phenyl, lower-alkyl-substitutedphenyls, halogenated phenyls, naphthyl, aminonaphthyls) having or nothaving a substituent [e.g., amino group, lower (1 to 4 carbon atoms)alkyl groups, halogens such as Cl and Br].

Organic ammonium components represented by Formulas (2) and (3) abovecan be obtained from organic amines exemplified below, which, however,are not to be construed as limiting the present invention.

Specifically, there may be mentioned

-   aliphatic amines such as hexylamine, pentylamine, octylamine,-   2-ethylhexylamine, di-(2-ethylhexyl)amine and dodecylamine;-   alicyclic amines such as cyclohexylamine, di-cyclohexylamine and    dihydroaziethylamine;-   alkoxyalkylamines such as 3-propoxypropylamine,-   di-(3-ethoxypropyl)amine, 3-butoxypropylamine, octoxypropylamine and    3-(2-ethylhexyloxy)propylamine;-   naphthylamines such as α-naphthylamine, β-naphthylamine,    1,2-naphthylenediamine, 1,5-naphthylenediamine and    1,8-naphthylenediamine;-   naphthylalkylamines such as 1-naphthylmethylamine;-   alkanol-group-containing amines such as N-cyclohexylethanolamine,    N-dodecylethanolamine and N-dodecylimino-di-ethanol;-   and guanidines (derivatives) such as 1,3-diphenylguanidine,-   1-o-tolylguanidine and di-o-tolylguanidine.

Of the organic ammonium components represented by Formula (2) 5 above,those that are particularly preferred are shown in Table 1. TABLE 1 R¹⁴R¹⁵ R¹⁶ R¹⁷ S-1 H H H

S-2 H H H —(CH₂)₃—O—CH₂(C₂H₅)—CH₂—C₄H₉ S-3 H H H

Of the organic ammonium components represented by Formula (3) above,those that are particularly preferred are shown in Table 2. TABLE 2 R¹⁸R¹⁹ R²⁰ R²¹ S-4 H

H

S-5 H

H

In particular, aromatic guanidines as shown in Table 2 are unlikely tovolatilize under heating in an extruding machine, an injection moldingmachine and the like. Hence, of the anthraquinone salt forming dyesrepresented by Formula (1) above, those having such an aromaticguanidine as the organic ammonium component are unlikely to decompose,even through processes such as thermal melting during molding, andexhibit excellent dispersibility in the molded product. As a result, themolded product obtained is excellent in laser ray transmission.

The anthraquinone salt forming dye used in the present invention has acolor such as blue, purple or green. As a colorant for the laser raytransmitting colored polyolefin resin composition of the presentinvention, there may be used an anthraquinone salt forming dyes havingvarious colors alone, or two species or more of such salt forming dyesin combination. Also, as a colorant for the laser ray transmittingcolored polyolefin resin composition of the present invention, there maybe used one species or two species or more of pigments or dyes that havean absorption band only outside the visible light absorption band of theanthraquinone salt forming dye or have an absorption band outside thevisible light in addition to visible light absorption band, and thatallows light transmission in the wavelength band of laser ray(wavelength from 800 nm to 1200 nm), along with the aforementionedanthraquinone salt forming dye. By blending dyes or pigments having acolor such as yellow or red, that are other colorants offering goodlaser transmission as described above, it is possible to impart variouscolors. For example, by combining a purple dye among the aforementionedanthraquinone salt forming dyes and another yellow colorant, it ispossible to impart a black color. Of the laser ray transmitting coloredpolyolefin resin compositions, black resin compositions are industriallyimportant.

As examples of such other colorants that are capable of imparting colorsto resin, there may be mentioned azo salt forming dyes and/oranthrapyridone dyes that exhibit chromatic colors such as yellow, orangeand red, and that transmit laser.

As specific examples of acid dyes corresponding to the anion componentsof azo salt forming dyes that can be used along with an anthraquinonesalt forming dye of Formula (1) in the laser ray transmitting coloredpolyolefin resin composition of the present invention, the followingexamples may be mentioned. Red acid dyes such as C.I. Acid Red 1, 3, 4,5, 7, 8, 9, 10, 12, 13, 14, 17, 18, 23, 24, 26, 27, 30, 33, 34, 35, 37,40, 41, 54, 60, 66, 70, 73, 74, 88, 97, 102, 112, 115, 135, 137, 138,141, 143, 144, 148, 150, 151, 176, 231 and 266; and yellow acid dyessuch as C.I. Acid Yellow 4, 9, 17, 18, 19, 23, 36, 41, 42, 49, 105, 199,200 and 219. However, the present invention is not limited by theseexamples.

As specific examples of acid dyes corresponding to the anion componentsof anthrapyridone salt forming dyes that can be used along with ananthraquinone salt forming dye of Formula (1) in the laser raytransmitting colored polyolefin resin composition of the presentinvention, there may be mentioned red acid dyes such as C.I. Acid Red80, 81, 82 and 143. However, the present invention is not limited bythese examples.

The amount of colorant used in the laser ray transmitting coloredpolyolefin resin composition of the present invention may, for example,be 0.01 to 10% by weight relative to polyolefin resin. The amount ispreferably 0.1 to 5% by weight, more preferably 0.1 to 1% by weight.

A master batch (high-concentration molded product) of the laser raytransmitting colored polyolefin resin composition of the presentinvention is obtained by, for example, blending polyolefin resin powderor pellets as a master batch base and a colorant containing at least ananthraquinone salt forming dye of Formula (1) above in a tumbler orsuper-mixer and the like, and then pelletizing or coarsely granulatingit by thermal melting in an extruder, batch-wise kneader, roll kneader,or the like. A master batch can also be obtained by, for example, addingthe aforementioned colorant to polyolefin resin for a master batch basewhile remaining in solution after synthesis, and then removing thesolvent.

By blending the thus-obtained colored pellets or coarsely granulatedcolorant (this colorant form is referred to as master batch in thepresent invention) with a polyolefin resin and molding this by aconventional method, it is possible to obtain a more uniform laser raytransmitting resin part of excellent laser transmission quality. Inparticular, when using a black mixed colorant of a combination of ananthraquinone salt forming dye and a plurality of colorants, this effectis remarkable.

As such, the master batch may contain the aforementioned colorant at 1to 30% by weight, for example, relative to the amount of polyolefinresin. The content ratio is preferably 5 to 15% by weight.

T_(colored resin)/T_(noncolored resin), i.e., the ratio ofT_(colored resin), the transmittance for a laser ray having a wavelengthof 940 nm in the laser ray transmitting colored polyolefin resincomposition of the present invention, and T_(noncolored resin), thetransmittance for a laser ray having a wavelength of 940 nm in anoncolored resin of the same but without a colorant, is preferably 0.8to 1.2.

The laser ray transmitting colored polyolefin resin composition of thepresent invention may contain appropriate amounts of various reinforcingmaterials according to its application and intended use. Thesereinforcing materials are not particularly limited, as long as it isusable for ordinary reinforcement of synthetic resins. For example,glass fiber, carbon fiber, other inorganic fibers, and organic fibers(aramid, polyphenylene sulfide, nylon, polyester, liquid crystalpolymer, etc.), etc. can be used, with preference given to glass fiberfor reinforcement of resins that require transparency. The fiber lengthof glass fiber is preferably 2 to 15 mm and the fiber diameter ispreferably 1 to 20 μm. The form of glass fiber is not subject tolimitation, and may be of any one, e.g., roving or milled fiber. Theseglass fibers may be used singly or in combination of two or more kinds.Their content is preferably 5 to 120% by weight relative to 100% byweight of polyolefin resin. If the content is less than 5% by weight, asufficient glass fiber-reinforcing effect is unlikely to be attained; ifthe content exceeds 120% by weight, moldability is likely to decrease.Their content is preferably 10 to 60% by weight, particularly preferably20 to 50% by weight.

The laser ray transmitting colored polyolefin resin composition of thepresent invention may contain appropriate amounts of various fillersaccording to its application and intended use. There can be used, forexample, tabular fillers such as mica, sericite and glass flake,silicates such as talc, kaolin, clay, wollastonite, bentonite, asbestosand alumina silicate, metal oxides such as alumina, silicon oxide,magnesium oxide, zirconium oxide and titanium oxide, carbonates such ascalcium carbonate, magnesium carbonate and dolomite, sulfates such ascalcium sulfate and barium sulfate, and particulate fillers such asglass beads, ceramic beads, boron nitride and silicon carbide. As anexample of a preferred filler in the present invention, there may bementioned talc. Although useful particle diameters of the filler rangewidely, from as fine as 0.03 μm to about 100 μm, those having particlediameters of 0.03 to 10 μm are preferred for the laser ray transmittingcolored polyolefin resin composition and method of laser welding of thepresent invention. The filler content is preferably 5 to 50% by weightrelative to 100% by weight of polyolefin resin. If the content is lessthan 5% by weight, a sufficient effect for a filler is unlikely to beattained; if the content exceeds 50% by weight, laser transmissiondecreases considerably. The content is preferably 10 to 50% by weight,particularly preferably 10 to 40% by weight.

The laser ray transmitting colored polyolefin resin composition of thepresent invention may also be formulated with various additives asnecessary. Such additives include, for example, auxochromic agents,dispersing agents, stabilizers, plasticizers, quality-improving agents,ultraviolet absorbents or light stabilizers, antioxidants, antistaticagents, lubricants, mold-releasing agents, crystallization promoters,crystal nucleating agents, and flame retardants.

The laser ray transmitting colored polyolefin resin composition of thepresent invention is obtained by blending raw materials by an optionallychosen method of blending. It is generally preferable that theseblending ingredients be homogenized to the maximum possible extent.Specifically, for example, all raw materials are blended and homogenizedin a mechanical mixer such as a blender, kneader, Banbury mixer, rollmixer or extruder to yield a colored polyolefin resin composition.Alternatively, after some raw materials are blended in a mechanicalmixer, the remaining ingredients are added, followed by further blendingand homogenization, to yield a resin composition. Additionally,previously dry-blended raw materials may be kneaded and homogenized in amolten state in a heated extruder, then extruded into a needle, whichneedle is then cut into desired length to yield a colored granular resincomposition (colored pellets).

Molding of the laser ray transmitting colored polyolefin resincomposition of the present invention can be achieved by variousprocedures in common use. For example, the laser ray transmittingcolored polyolefin resin composition of the present invention can bemolded using colored pellets in a processing machine such as anextruder, injection molding machine or roll mill, and can also be moldedby blending polyolefin resin pellets or powder, a milled colorant, andwhere necessary various additives, in an appropriate mixer, and moldingthis blend using a processing machine. Any commonly used method ofmolding can be adopted, e.g., injection molding, extrusion molding,compression molding, foaming molding, blow molding, vacuum molding,injection blow molding, rotation molding, calender molding, and solutioncasting. By such molding, laser ray transmitting materials in variousshapes can be obtained.

The method of laser welding of the present invention comprises welding aportion of contact of a laser ray transmitting material comprising theaforementioned laser ray transmitting colored thermoplastic resincomposition and a laser ray absorbing material by irradiating laser rayso that the laser ray transmits the laser ray transmitting material andis absorbed in the laser ray absorbing material with the laser raytransmitting material and the laser ray absorbing material in contactwith each other.

As examples of combinations of resins that permit laser welding in themethod of laser welding of the present invention, there may be mentioneda combination of polypropylene resins, a combination of polyethyleneresins, a combination of a polypropylene resin and a polyethylene resin,a combination of a polypropylene resin and a thermoplastic elastomer(particularly an olefin thermoplastic elastomer), and a combination of apolypropylene resin and a thermoplastic resin (e.g., polyamide andpolycarbonate).

Generally, advantages of laser welding include increased degrees offreedom for the shapes of the molds for the molded resin products oflaser ray transmitting material and laser ray absorbing material to bewelded because of the capability of 3-dimensional welding, improvedappearance because of freedom from burrs on the welded surface unlike invibration welding, and applicability to electronic components because offreedom from vibration and wear dust. Conversely, its disadvantagesinclude the necessity of pre-investment in equipment known as laserwelding machine, and possible gap formation between the parts forwelding, due to sink during the molding of the laser ray transmittingmaterial and laser ray absorbing material to be welded, both of whichare made of resin. The problem with this gap, in particular, is ofgreatest concern in performing laser welding; there are many cases wherea jig for fixture such as a clamp is made on a case-by-case basis toadapt it to the shapes of the parts to be welded. It is known that if agap of 0.02 mm occurs, welding strength halves compared to the gap-freestate, and that welding fails if the gap is 0.05 mm or more.

Available laser welding machines include the scanning type, in whichlaser moves, the masking type, in which the parts to be welded move, andthe type in which laser rays are irradiated to the parts to be weldedfrom multiple directions simultaneously. It is the scanning type whichis drawing attention from the automobile industry, with a scanning speedof 5 m/min serving as the criterion for production tact time.

Because laser welding relies on the conversion of light energy of laserto heat energy, welding performance is considerably influenced by laserwelding conditions. Generally, the amount of heat produced by irradiatedlaser on the absorbent part surface can be calculated by the equationbelow:Amount of heat on absorbent part surface (J/mm²)=laser output(W)/[scanning speed (mm/sec)×ray spot diameter of laser (mm)]

To increase production efficiency, the scanning speed must be increased;to achieve this, a laser welding machine of the high output type isnecessary.

Additionally, to increase welding strength, some heat on the surface ofthe laser absorbing part is necessary. This heat must be determined bycombining various conditions such as increased output setting, decreasedscanning speed, and decreased spot diameter. Since too great surfaceheat provided by laser affects the appearance of the welded portion and,in the extreme case, causes the laser absorbing part to smoke, laserwelding condition settings are important and the laser transmittance ofthe laser ray transmitting resin material to be welded is of paramountimportance. Considering the above-described conditions, it is preferablethat in the method of laser welding of the present invention, a contactportion of a laser ray transmitting material and a laser ray absorbingmaterial be welded in a state that satisfies Formula (A). By doing so, awelded product having a practically unproblematic welding strength isobtained.Q=P/(S·φ)>0.4   (A)Where

-   Q: amount of heat on surface of laser ray absorbing material (J/mm²)-   P: output (W) of laser that transmits laser ray transmitting    material-   S: laser scanning speed (mm/sec)-   φ: spot diameter of laser (mm)

It is preferable that the laser ray absorbing material comprise a laserray absorbing colored resin composition incorporating carbon blackand/or another laser ray absorbent, for example, as a laser rayabsorbing black colorant.

As substances that can be used as both the aforementioned black colorantand laser ray absorbent, there may be mentioned carbon black, nigrosine,aniline black and so on. As examples of other laser ray absorbents,there may be mentioned phthalocyanine, naphthalocyanine, perilene,quaterylene, metal complexes, squaric acid derivatives, immonium dyes,polymethine, etc.;

-   two or more thereof may be blended to obtain a black laser ray    absorbent. Furthermore, it is also possible to use the    aforementioned laser ray transmitting colorant and laser ray    absorbent in combination. A preferred laser absorbing black colorant    is a combination of carbon black and nigrosine.

As the carbon black with good laser absorbability, there may bementioned those 15 to 100 nm (preferably 15 to 50 nm) in primaryparticle diameter, and those 30 to 500 m²/g (preferably 100 to 300 m²/g)in BET specific surface area.

The amount of colorant used in such a laser ray absorbing colored resincomposition may be, for example, 0.01 to 10% by weight relative topolyolefin resin, and is preferably 0.05 to 5% by weight. The laser rayabsorbing material can be produced in the same manner as the laser raytransmitting material except for the containment of a laser rayabsorbent.

As examples of major applications of the laser ray transmitting coloredpolyolefin resin composition and method of laser welding of the presentinvention, there may be mentioned automobile parts. More specifically,there may be mentioned, for example, instrument panels in interiors andresonators (mufflers) in engine rooms. Conventionally, use of adhesiveshas been difficult in joining polyolefin resin parts; to achieve theirjoining, special procedures such as surface treatment have beennecessary. When laser welding is used, there is no need forpretreatment, alloying of resin and the like; laser welding can be saidto surpass adhesives also in terms of strength and recyclability.

EXAMPLES

The present invention is hereinafter described in more detail by meansof, but is not limited to, the following examples.

Referring to Table 3, the colorants prepared in Production Examples 1 to8 were used in the respective Examples, and the colorants prepared inComparative Production Examples 1 to 8 were used in the respectiveComparative Examples. All these colorants were single salt forming dyesor mixed dyes of two or more kinds of salt forming dyes. The anioniccomponents shown as the Example Compounds above correspond to the aciddyes for the respective Production Examples, and the organic ammoniumcomponents shown in Table 1 or 2 correspond to the organic amines forthe respective Production Examples. The salt forming dyes of each ofC.I. Acid Red 266 (monoazo acid dye), C.I. Acid Yellow 49 (monoazo aciddye), C.I. Acid Red 143 (anthrapyridone acid dye), C.I. Acid Red 97(disazo acid dye), C.I. Acid Red 144 (disazo acid dye), C.I. Acid Yellow42 (monoazo acid dye), C.I. Acid Violet 43 (anthraquinone acid dye),C.I. Acid Blue 41 (anthraquinone acid dye), C.I. Acid Blue 62(anthraquinone acid dye) and C.I. Acid Blue 260 (anthraquinone acid dye)and each organic amine in Production Examples 4 to 8 and ComparativeProduction Examples 1 to 8 were obtained by a salt-forming reaction ofeach acid dye and each organic amine.

Each of the colorants of Production Examples 1 to 3 and ComparativeProduction Examples 1 to 4 comprises a single salt forming dye, whereasthe colorants of Production Examples 4 to 8 and Comparative ProductionExamples 5 to 8 are black colorants prepared by blending a plurality ofsalt forming dyes according to the respective content ratios by weightshown in the content ratio column using a simple mechanical mixer.

For example, the colorant of Production Example 1 was produced asdescribed below. First, 10 g of an anthraquinone acid dye represented byExample Compound (1)-1 was dispersed in 500 ml of water. Separately, 5mg of hydrochloric acid and 7 g of the organic amine S-4 were dissolvedin 150 ml of water. This solution was added drop by drop to thedispersion liquid of said anthraquinone acid dye at room temperature,and the reaction was carried out with stirring at 40 to 45° C. for 1hour. Subsequently, the temperature was increased to 60 to 70° C. tomake the reaction product particulate, and the reaction mixture wasadjusted to a pH of 6.5 to 7.5 and stirred for 1 hour. The reactionmixture was filtered and the cake filtered out was washed with water, toyield 12.0 g (yield 75%) of an anthraquinone salt forming dye. TABLE 3Organic Content Acid dye amine ratio Production Example 1 ExampleCompound (1)-1 S-4 — Production Example 2 Example Compound (1)-2 S-4 —Production Example 3 Example Compound (1)-4 S-4 — Production Example 4Example Compound (1)-1 S-4 5 C.I. Acid Red 266 S-4 3 C.I. Acid Yellow 49S-4 2 Production Example 5 Example Compound (1)-2 S-4 2 C.I. Acid Red143 S-4 1 Production Example 6 Example Compound (1)-3 S-4 1 C.I. AcidRed 97 S-5 1 Production Example 7 Example Compound (1)-1 S-4 2 C.I. AcidRed 144 S-4 2 C.I. Acid Yellow 42 S-1 3 Production Example 8 ExampleCompound (1)-4 S-4 5 C.I. Acid Yellow 42 S-4 1 Comparative C.I. AcidViolet 43 S-4 — Production Example 1 Comparative C.I. Acid Blue 41 S-4 —Production Example 2 Comparative C.I. Acid Blue 62 S-4 — ProductionExample 3 Comparative C.I. Acid Blue 260 S-4 — Production Example 4Comparative C.I. Acid Blue 62 S-4 5 Production Example 5 C.I. Acid Red266 S-4 2 C.I. Acid Yellow 42 S-4 1 Comparative C.I. Acid Violet 43 S-43 Production Example 6 C.I. Acid Yellow 49 S-4 1 Comparative C.I. AcidBlue 41 S-3 5 Production Example 7 C.I. Acid Red 266 S-3 3 C.I. AcidYellow 49 S-3 2 Comparative C.I. Acid Blue 260 S-4 5 Production Example8 C.I. Acid Red 266 S-4 3 C.I. Acid Yellow 42 S-4 2

Example 1

Fiber-Reinforced polypropylene Resin . . . 400 g (manufactured by JapanPolychem, Product Number: HG30U)

Colorant of Production Example 1 . . . 0.80 g

The above ingredients were placed in a stainless steel tumbler and mixedwith stirring for 1 hour. The blend obtained was injection-molded by anordinary method at a cylinder temperature of 220° C. and a moldtemperature of 40° C. using an injection molding machine (manufacturedby Toyo Machinery & Metal Co., Ltd., product number: Si-50); a uniformlycolored blue test piece having good appearance and surface gloss wasobtained.

Example 2

Fiber-Reinforced polypropylene Resin . . . 400 g (Manufactured by JapanPolychem, Product Number: HG30U)

Colorant of Production Example 2 . . . 0.80 g

The above ingredients were placed in a stainless steel tumbler and mixedwith stirring for 1 hour. The blend obtained was injection-molded by anordinary method at a cylinder temperature of 220° C. and a moldtemperature of 40° C. using an injection molding machine (manufacturedby Toyo Machinery & Metal Co., Ltd., product number: Si-50); a uniformlycolored green test piece having good appearance and surface gloss wasobtained.

Example 3

Fiber-Reinforced polypropylene Resin . . . 400 g (Manufactured by JapanPolychem, Product Number: HG30U)

Colorant of Production Example 3 . . . 0.80 g

The above ingredients were placed in a stainless steel tumbler and mixedwith stirring for 1 hour. The blend obtained was injection-molded by anordinary method at a cylinder temperature of 220 ° C. and a moldtemperature of 40° C. using an injection molding machine (manufacturedby Toyo Machinery & Metal Co., Ltd., product number: Si-50); a uniformlycolored purple test piece having good appearance and surface gloss wasobtained.

Example 4

Fiber-Reinforced polypropylene Resin . . . 400 g (Manufactured by JapanPolychem, Product Number: HG30U)

Colorant of Production Example 4 . . . 1.20 g

The above ingredients were placed in a stainless steel tumbler and mixedwith stirring for 1 hour. The blend obtained was injection-molded by anordinary method at a cylinder temperature of 220° C. and a moldtemperature of 40° C. using an injection molding machine (manufacturedby Toyo Machinery & Metal Co., Ltd., product number: Si-50); a uniformlycolored black test piece having good appearance and surface gloss wasobtained.

Example 5

Fiber-Reinforced polypropylene Resin . . . 400 g (Manufactured by JapanPolychem, Product Number: HG30U)

Colorant of Production Example 5 . . . 1.20 g

The above ingredients were placed in a stainless steel tumbler and mixedwith stirring for 1 hour. The blend obtained was injection-molded by anordinary method at a cylinder temperature of 220° C. and a moldtemperature of 40° C. using an injection molding machine (manufacturedby Toyo Machinery & Metal Co., Ltd., product number: Si-50); a uniformlycolored black test piece having good appearance and surface gloss wasobtained.

Example 6

Fiber-Reinforced polypropylene Resin . . . 400 g (Manufactured by JapanPolychem, Product Number: HG30U)

Colorant of Production Example 6 . . . 1.20 g

The above ingredients were placed in a stainless steel tumbler and mixedwith stirring for 1 hour. The blend obtained was injection-molded by anordinary method at a cylinder temperature of 220° C. and a moldtemperature of 40° C. using an injection molding machine (manufacturedby Toyo Machinery & Metal Co., Ltd., product number: Si-50); a uniformlycolored black test piece having good appearance and surface gloss wasobtained.

Example 7

Fiber-Reinforced polypropylene Resin . . . 400 g (Manufactured by JapanPolychem, Product Number: HG30U)

Colorant of Production Example 7 . . . 1.20 g

The above ingredients were placed in a stainless steel tumbler and mixedwith stirring for 1 hour. The blend obtained was injection-molded by anordinary method at a cylinder temperature of 220° C. and a moldtemperature of 40° C. using an injection molding machine (manufacturedby Toyo Machinery & Metal Co., Ltd., product number: Si-50); a uniformlycolored black test piece having good appearance and surface gloss wasobtained.

Example 8

Fiber-Reinforced polypropylene Resin . . . 400 g (Manufactured by JapanPolychem, Product Number: HG30U)

Colorant of Production Example 8 . . . 1.20 g

The above ingredients were placed in a stainless steel tumbler and mixedwith stirring for 1 hour. The blend obtained was injection-molded by anordinary method at a cylinder temperature of 220° C. and a moldtemperature of 40° C. using an injection molding machine (manufacturedby Toyo Machinery & Metal Co., Ltd., product number: Si-50); a uniformlycolored black test piece having good appearance and surface gloss wasobtained.

Example 9

Polypropylene Resin (Not Reinforced) . . . 900 g (Manufactured by JapanPolychem, Product Number: BC05B)

Colorant of Production Example 8 . . . 100 g

The above ingredients were placed in a stainless steel tumbler and mixedwith stirring for 1 hour. The blend obtained was mixed in a molten stateat a cylinder temperature of 220° C. using a single-shaft extruder(manufactured by Enpura Sangyo, product number: E30SV). Subsequently, itwas cooled in a water chamber and then cut using a pelletizer andsubjected to a drying process to yield a black master batch.

Fiber-Reinforced polypropylene Resin . . . 384 g (Manufactured by JapanPolychem, Product Number: HG30U)

Black Master Batch . . . 12 g

The above ingredients were placed in a stainless steel tumbler and mixedwith stirring for 20 minutes. The blend obtained was injection-molded byan ordinary method at a cylinder temperature of 220° C. and a moldtemperature of 40 ° C. using an injection molding machine (manufacturedby Toyo Machinery & Metal Co., Ltd., product number: Si-50); a uniformlycolored black test piece having good appearance and surface gloss wasobtained.

Example 10

Low-Density polyethylene Resin . . . 400 g (Manufactured by JapanPolychem, Product Number: LC604)

Colorant of Production Example 8 . . . 1.20 g

The above ingredients were placed in a stainless steel tumbler and mixedwith stirring for 1 hour. The blend obtained was injection-molded by anordinary method at a cylinder temperature of 180° C. and a moldtemperature of 40° C. using an injection molding machine (manufacturedby Toyo Machinery & Metal Co., Ltd., product number: Si-50); a uniformlycolored black test piece having good appearance and surface gloss wasobtained.

Example 11

High-Density polyethylene Resin . . . 400 g (Manufactured by JapanPolychem, Product Number: HJ290)

Colorant of Production Example 8 . . . 1.20 g

The above ingredients were placed in a stainless steel tumbler and mixedwith stirring for 1 hour. The blend obtained was injection-molded by anordinary method at a cylinder temperature of 210° C. and a moldtemperature of 40° C. using an injection molding machine (manufacturedby Toyo Machinery & Metal Co., Ltd., product number: Si-50); a uniformlycolored black test piece having good appearance and surface gloss wasobtained.

Example 12

Polyolefin Cross-Linked Thermoplastic Elastomer . . . 400 g(Manufactured by Advanced Elastomer Systems Japan, Product Cumber:Santoprene 8211-65)

Colorant of Production Example 1 . . . 0.40 g

The above ingredients were placed in a stainless steel tumbler and mixedwith stirring for 1 hour. The blend obtained was injection-molded by anordinary method at a cylinder temperature of 200° C. and a moldtemperature of 40° C. using an injection molding machine (manufacturedby Toyo Machinery & Metal Co., Ltd., product number: Si-50); a uniformlycolored blue test piece having good appearance and surface gloss wasobtained.

Example 13

Polypropylene Resin (Not Reinforced) . . . 790 g (Manufactured by JapanPolychem, Product Number: BC05B)

Colorant of Production Example 8 . . . 10 g

Talc . . . 200 g

The above ingredients were mixed with stirring in a high-speed mixer for20 minutes. The blend obtained was mixed in a molten state at a cylindertemperature of 220° C. using a single-shaft extruder (manufactured byEnpura Sangyo, product number: E30SV). Subsequently, it was cooled in awater chamber and then cut using a pelletizer and subjected to a dryingprocess to yield black pellets.

Subsequently, they were injection-molded by an ordinary method at acylinder temperature of 200° C. and a mold temperature of 40° C. usingan injection molding machine (manufactured by Toyo Machinery & MetalCo., Ltd., product number: Si-50); a uniformly colored black test piecehaving good appearance and surface gloss was obtained.

Comparative Example 1

Fiber-Reinforced polypropylene Resin . . . 400 g (Manufactured by JapanPolychem, Product Number: HG30U)

Colorant of Comparative Production Example 1 . . . 0.80 g

The above ingredients were placed in a stainless steel tumbler and mixedwith stirring for 1 hour. The blend obtained was injection-molded by anordinary method at a cylinder temperature of 220 ° C. and a moldtemperature of 40° C. using an injection molding machine (manufacturedby Toyo Machinery & Metal Co., Ltd., product number: Si-50); a purpletest piece was obtained.

Comparative Example 2

Fiber-Reinforced polypropylene Resin . . . 400 g (Manufactured by JapanPolychem, Product Number: HG30U)

Colorant of Comparative Production Example 2 . . . 0.80 g

The above ingredients were placed in a stainless steel tumbler and mixedwith stirring for 1 hour. The blend obtained was injection-molded by anordinary method at a cylinder temperature of 220° C. and a moldtemperature of 40° C. using an injection molding machine (manufacturedby Toyo Machinery & Metal Co., Ltd., product number: Si-50); a blue testpiece was obtained.

Comparative Example 3

Fiber-Reinforced polypropylene Resin . . . 400 g (Manufactured by JapanPolychem, Product Number: HG30U)

Colorant of Comparative Production Example 3 . . . 0.80 g

The above ingredients were placed in a stainless steel tumbler and mixedwith stirring for 1 hour. The blend obtained was injection-molded by anordinary method at a cylinder temperature of 220° C. and a moldtemperature of 40° C. using an injection molding machine (manufacturedby Toyo Machinery & Metal Co., Ltd., product number: Si-50); a blue testpiece was obtained.

Comparative Example 4

Fiber-Reinforced polypropylene Resin . . . 400 g (Manufactured by JapanPolychem, Product Number: HG30U)

Colorant of Comparative Production Example 4 . . . 0.80 g

The above ingredients were placed in a stainless steel tumbler and mixedwith stirring for 1 hour. The blend obtained was injection-molded by anordinary method at a cylinder temperature of 220° C. and a moldtemperature of 40° C. using an injection molding machine (manufacturedby Toyo Machinery & Metal Co., Ltd., product number: Si-50); a blue testpiece was obtained.

Comparative Example 5

Fiber-Reinforced polypropylene Resin . . . 400 g (Manufactured by JapanPolychem, Product Number: HG30U)

Colorant of Comparative Production Example 5 . . . 0.80 g

The above ingredients were placed in a stainless steel tumbler and mixedwith stirring for 1 hour. The blend obtained was injection-molded by anordinary method at a cylinder temperature of 220° C. and a moldtemperature of 40° C. using an injection molding machine (manufacturedby Toyo Machinery & Metal Co., Ltd., product number: Si-50); a blacktest piece was obtained.

Comparative Example 6

Fiber-Reinforced polypropylene Resin . . . 400 g (Manufactured by JapanPolychem, Product Number: HG30U)

Colorant of Comparative Production Example 6 . . . 0.80 g

The above ingredients were placed in a stainless steel tumbler and mixedwith stirring for 1 hour. The blend obtained was injection-molded by anordinary method at a cylinder temperature of 220° C. and a moldtemperature of 40° C. using an injection molding machine (manufacturedby Toyo Machinery & Metal Co., Ltd., product number: Si-50); a blacktest piece was obtained.

Comparative Example 7

Fiber-Reinforced polypropylene Resin . . . 400 g (Manufactured by JapanPolychem, Product Number: HG30U)

Colorant of Comparative Production Example 7 . . . 1.20 g

The above ingredients were placed in a stainless steel tumbler and mixedwith stirring for 1 hour. The blend obtained was injection-molded by anordinary method at a cylinder temperature of 220° C. and a moldtemperature of 40° C. using an injection molding machine (manufacturedby Toyo Machinery & Metal Co., Ltd., product number: Si-50); a blacktest piece was obtained.

Comparative Example 8

Fiber-Reinforced polypropylene Resin . . . 400 g (Manufactured by JapanPolychem, Product Number: HG30U)

Colorant of Comparative Production Example 8 . . . 1.20 g

The above ingredients were placed in a stainless steel tumbler and mixedwith stirring for 1 hour. The blend obtained was injection-molded by anordinary method at a cylinder temperature of 220° C. and a moldtemperature of 40° C. using an injection molding machine (manufacturedby Toyo Machinery & Metal Co., Ltd., product number: Si-50); a blacktest piece was obtained.

Physical Property Assessments

The laser ray transmitting colored polyolefin resin compositionsobtained in Examples 1 to 8 and Comparative Examples 1 to 8 andsimilarly molded uncolored polyolefin resin (PP) test pieces weresubjected to physical property assessments by the methods describedbelow. The results are shown in Tables 4 and 5 below.

(1) Determination of Transmittance

Each test piece was set to a spectrophotometer (manufactured by JASCOCorporation, product number: V-570 model), and its transmittance wasdetermined over a wavelength range of λ=400 to 1200 nm. Tables 4 and 5show the transmittances of respective test pieces for semiconductorlaser ray at a wavelength of 940 nm.

(2) Anti-Sublimation Test and Assessment

A test piece with a white PET (polyethylene terephthalate resin) filmapplied thereto was placed in an oven and allowed to stand at 160° C.for 3 hours. Thereafter, the PET film was removed from the test pieceand applied to a colorless transparent OHP (overhead projector) sheet tofacilitate observation. If the dye had not migrated to the PET film, thedye was judged to have anti-sublimation quality.

(3) Heat Resistance Test and Assessment

In the injection molding in Examples 1 to 8 and Comparative Examples 1to 8 above, a blend of ingredients was subjected to an ordinary shot,and thereafter the remaining portion of the blend was retained in thecylinder at 220° C. for 15 minutes; injection molding was then conductedto yield test pieces.

If the discoloration/fading of the color of the test piece obtainedafter the retainment in the cylinder for 15 minutes had not advancedcompared to the color of the test piece obtained by an ordinary shot, itwas judged to be resistant to heat.

(4) Anti-Bleeding Test and Assessment

Each of the test pieces obtained in Examples 1 to 8 and ComparativeExamples 1 to 8 above and a white test piece colored with titanium oxidewere superposed in the direction of thickness, and was allowed to standat 80° C. for 100 hours under a pressure of 200 g (1.96 N)/cm² exertedin the direction of superposition. Subsequently, degree of colorantmigration to the white test piece was examined. If the colorant had notmigrated to the white test piece, the test piece was judged to haveanti-bleeding quality.

(5) Preparation of Laser Absorbing Test Pieces for Laser Welding Testand Laser Welding Test

laser absorbing test pieces (laser ray absorbing materials)incorporating a polyolefin resin were prepared as described below.

Fiber-Reinforced polypropylene Resin . . . 400 g (Manufactured by JapanPolychem, Product Number: HG30U)

Carbon Black . . . 0.80 g

The above ingredients were placed in a stainless steel tumbler and mixedwith stirring for 1 hour. The blend obtained was injection-molded by anordinary method at a cylinder temperature of 220° C. and a moldtemperature of 40° C. using an injection molding machine (manufacturedby Toyo Machinery & Metal Co., Ltd., product number: Si-50); a uniformlycolored black laser absorbing test piece having good appearance andsurface gloss was obtained.

Low-density polyethylene Resin . . . 400 g (Manufactured by JapanPolychem, Product Number: LC604)

Carbon Black . . . 0.80 g

The above ingredients were placed in a stainless steel tumbler and mixedwith stirring for 1 hour. The blend obtained was injection-molded by anordinary method at a cylinder temperature of 180° C. and a moldtemperature of 40° C. using an injection molding machine (manufacturedby Toyo Machinery & Metal Co., Ltd., product number: Si-50); a uniformlycolored black test piece having good appearance and surface gloss wasobtained.

High-density polyethylene Resin . . . 400 g (Manufactured by JapanPolychem, Product Number: HJ290)

Carbon Black . . . 0.80 g

The above ingredients were placed in a stainless steel tumbler and mixedwith stirring for 1 hour. The blend obtained was injection-molded by anordinary method at a cylinder temperature of 210° C. and a moldtemperature of 40° C. using an injection molding machine (manufacturedby Toyo Machinery & Metal Co., Ltd., product number: Si-50); a uniformlycolored black test piece having good appearance and surface gloss wasobtained.

Polyolefin Cross-Linked Thermoplastic Elastomer . . . 400 g(Manufactured by Advanced Elastomer Systems Japan, Product Number:Santoprene 8211-65)

Carbon Black . . . 0.40 g

The above ingredients were placed in a stainless steel tumbler and mixedwith stirring for 1 hour. The blend obtained was injection-molded by anordinary method at a cylinder temperature of 200° C. and a moldtemperature of 40° C. using an injection molding machine (manufacturedby Toyo Machinery & Metal Co., Ltd., product number: Si-50); a uniformlycolored black test piece having good appearance and surface gloss wasobtained.

Talc-Containing polypropylene Resin . . . 400 g

Carbon Black . . . 2.00 g

The above ingredients were placed in a stainless steel tumbler and mixedwith stirring for 1 hour. The blend obtained was injection-molded by anordinary method at a cylinder temperature of 200° C. and a moldtemperature of 40° C. using an injection molding machine (manufacturedby Toyo Machinery & Metal Co., Ltd., product number: Si-50); a uniformlycolored black test piece having good appearance and surface gloss wasobtained

As shown in FIG. 1 (lateral view) and FIG. 2 (oblique view), each testpiece 10 of Examples 1 to 11 and Comparative Examples 1 to 8 and thelaser absorbing test piece 12 [all 60 mm length×18 mm width×3 mmthickness (1.5 mm thickness for 20 mm of the length)], were superposedwith respective portions 20 mm length×18 mm width×1.5 mm thickness incontact with each other.

The superposed portion was irradiated with a laser beam 14 (spotdiameter 0.6 mm) from above the test piece 10 (in the Figure) using adiode laser of 30 W output [wavelength: 940 nm, continuous](manufactured by Fine Devices Company), while scanning at a variablescanning speed in the lateral direction (direction perpendicular to theplane of FIG. 1). Welding was conducted between test pieces of the samematerial.

If the laser transmits the test piece 10 and is absorbed in the laserabsorbing test piece 12, the laser absorbing test piece 12 wouldgenerate heat, by which heat the laser absorbing test piece 12 is moltenaround the portion that has absorbed the laser ray, and the test piece10 is also molten, the resins of the two test pieces fuse together, andupon cooling the two pieces are joined together. In FIG. 2, 16 indicatesthe welded portion.

(6) Tensile Strength Test

The welded product obtained in (5) above was subjected to a tensilestrength test on both the test piece 10 side and the laser absorbingtest piece 12 side in the longitudinal direction (left-right directionin FIG. 1) at a pulling speed of 10 mm/min in accordance with JISK7113-1995 using a tensile strength tester (AG-50kNE, manufactured byShimadzu Corporation), in order to determine its tensile weldingstrength.

In Tables 4 and 5, Examples 1 to 8 describe the results forpolypropylenes, Example 9 for a low-density polyethylene (LDPE), Example10 for a high-density polyethylene (HDPE), and Example 11 for athermoplastic elastomer (elastomer). TABLE 4 (6) Tensile strength (5)Laser welding test test (1) (2) Anti- (3) Heat (4) Anti- ScanningSurface Welding Tensile Transmittance sublimation resistance bleedingspeed heat state strength test (%) test test test (mm/sec) (J/mm²)appearance (Mpa) GF-PP 48 — — — Example 1 46 Good Good Good 30 0.77 Noproblem 14.8 45 0.51 No problem 11.1 60 0.38 No problem 3.7 Example 2 45Good Good Good 30 0.75 No problem 14.2 45 0.50 No problem 10.0 60 0.37No problem 2.5 Example 3 45 Good Good Good 30 0.75 No problem 14.5 450.50 No problem 10.7 60 0.37 No problem 3.2 Example 4 45 Good Good Good30 0.75 No problem 14.1 45 0.50 No problem 10.3 60 0.37 No problem 2.9Example 5 44 Good Good Good 30 0.73 No problem 13.5 45 0.48 No problem11.2 60 0.36 No problem 3.0 Example 6 44 Good Good Good 30 0.73 Noproblem 14.0 45 0.48 No problem 10.8 60 0.36 No problem 3.7 Example 7 45Good Good Good 30 0.75 No problem 14.8 45 0.50 No problem 10.6 60 0.37No problem 3.0 Example 8 44 Good Good Good 30 0.73 No problem 14.2 450.48 No problem 11.4 60 0.36 No problem 3.6 Example 9 47 Good Good Good30 0.78 No problem 15.7 45 0.52 No problem 12.3 60 0.39 No problem 5.8LDPE 58 — — — Example 10 53 Good Good Good 30 0.88 No problem 18.1 450.59 No problem 17.2 60 0.44 No problem 15.7 HDPE 54 — — — Example 11 49Good Good Good 30 0.82 No problem 19.5 45 0.54 No problem 18.6 60 0.40No problem 15.1 Elastomer 41 — — — Example 12 33 Good Good Good 10 1.55No problem 1.1 15 1.03 No problem 0.9 Talc PP 30 — — — Example 13 26Good Good Good 10 1.30 No problem 13.4

TABLE 5 (6) Tensile strength (5) Laser welding test test (1) (2) Anti-(3) Heat (4) Anti- Scanning Surface Welding Tensile Transmittancesublimation resistance bleeding speed heat state strength test (%) testtest test (mm/sec) (J/mm²) appearance (Mpa) Comparative 46 UnacceptableGood Good 30 0.77 No problem 14.5 Example 1 45 0.51 No problem 12.3 600.38 No problem 3.3 Comparative 43 Unacceptable Good Good 30 0.71 Noproblem 13.2 Example 2 45 0.47 No problem 11.4 60 0.35 No problem 1.8Comparative 46 Unacceptable Good Unacceptable 30 0.77 No problem 13.9Example 3 45 0.51 No problem 11.9 60 0.38 No problem 3.5 Comparative 44Unacceptable Good Good 30 0.73 No problem 13.8 Example 4 45 0.48 Noproblem 11.6 60 0.36 No problem 2.8 Comparative 47 Unacceptable GoodUnacceptable 30 0.78 No problem 14.8 Example 5 45 0.52 No problem 12.060 0.39 No problem 3.6 Comparative 45 Unacceptable Good Good 30 0.75 Noproblem 14.7 Example 6 45 0.50 No problem 11.4 60 0.37 No problem 3.9Comparative 43 Unacceptable Good Good 30 0.71 No problem 13.0 Example 745 0.47 No problem 10.1 60 0.35 No problem 2.1 Comparative 43Unacceptable Good Good 30 0.71 No problem 13.4 Example 8 45 0.47 Noproblem 10.6 60 0.35 No problem 1.9

The colored polyolefin resin compositions of the Comparative Exampleswere all judged to be unacceptable in the anti-sublimation test. Thecolored polyoferin resin compositions of Comparative Examples 3 and 5were also judged to be unacceptable in the anti-bleeding test.

1. Laser ray transmitting colored polyolefin resin compositioncontaining an anthraquinone salt forming dye represented by Formula (1)below and a red azo salt forming dye, the polyolefin resin compositioncontaining 5 to 50% by weight of talc relative to said polyolefin resin:

Formula (1), each of A and B independently represents —NH— or —O—, eachof R¹ to R³ independently represents hydrogen, an amino group, a hydroxygroup or a halogen, each of R⁴ to R¹³ independently represents hydrogen,an alkyl group, a nitro group or a sulfonic group, Ki^(n+) represents anorganic ammonium ion, m represents 1 or 2, and n represents 1 or 2; thesulfonic group is —SO₃ or SO₃M, the number of —SO₃ being m, Mrepresenting hydrogen or an alkali metal, and each of M may be identicalor not provided that the number of SO₃M is 2 or more.
 2. Laser raytransmitting colored polyolefin resin composition of claim 1, whichcontains 10 to 40% by weight of the talc relative to said polyolefinresin.
 3. Laser ray transmitting colored polyolefin resin composition ofclaim 1, wherein said polyolefin resin is polypropylene resin.
 4. Methodof laser welding comprising welding a portion of contact of a laser raytransmitting material comprising a laser ray transmitting coloredpolyolefin resin composition containing an anthraquinone salt formingdye represented by Formula (1) below and a red azo salt forming dye, thepolyolefin resin composition containing 5 to 50% by weight of talcrelative to said polyolefin resin, and a laser ray absorbing material byirradiating laser ray so that the laser ray transmits the laser raytransmitting material and is absorbed in the laser ray absorbingmaterial with the laser ray transmitting material and the laser rayabsorbing material in contact with each other:

in Formula (1), each of A and B independently represents —NH— or —O—,each of R¹ to R³ independently represents hydrogen, an amino group, ahydroxy group or a halogen, each of R⁴ to R¹³ independently representshydrogen, an alkyl group, a nitro group or a sulfonic group, Ki^(n+)represents an organic ammonium ion, m represents 1 or 2, and nrepresents 1 or 2; the sulfonic group is —SO₃ or SO₃M, the number of—SO₃ being m, M representing hydrogen or an alkali metal, and each of Mmay be identical or not provided that the number of SO₃M is 2 or more.5. Method of laser welding of claim 4, wherein said polyolefin resin ispolypropylene resin and the laser ray absorbing material comprises alaser ray absorbing colored resin composition incorporating carbon blackand/or another laser absorbing colorant.
 6. Method of laser welding ofclaim 4, wherein a contact portion of the laser ray transmittingmaterial and the laser ray absorbing material is welded in a state thatsatisfies Formula (A):Q=P/(S·φ)>0.4   (A) where Q: amount of heat on surface of laser rayabsorbing material (J/mm²) P: output (W) of laser that laser raytransmitting material transmits S: laser scanning speed (mm/sec) φ: spotdiameter of laser (mm).
 7. Laser ray transmitting colored polyolefinresin composition containing an anthraquinone salt forming dyerepresented by Formula (1) below and a red azo salt forming dye, saidpolyolefin resin being a polyolefin elastomer:

in Formula (1), each of A and B independently represents —NH— or —O—,each of R¹ to R³ independently represents hydrogen, an amino group, ahydroxy group or a halogen, each of R⁴ to R¹³ independently representshydrogen, an alkyl group, a nitro group or a sulfonic group, Ki^(n+)represents an organic ammonium ion, m represents 1 or 2, and nrepresents 1 or 2; the sulfonic group is —SO₃ or SO₃M, the number of—SO₃ being m, M representing hydrogen or an alkali metal, and each of Mmay be identical or not provided that the number of SO₃M is 2 or more.8. Method of laser welding comprising welding a portion of contact of alaser ray transmitting material comprising a laser ray transmittingcolored polyolefin resin composition containing an anthraquinone saltforming dye represented by Formula (1) below and a red azo salt formingdye, said polyolefin resin being a polyolefin elastomer, and a laser rayabsorbing material by irradiating laser ray so that the laser raytransmitting material transmits the laser ray and the laser ray isabsorbed in the laser ray absorbing material with the laser raytransmitting material and the laser ray absorbing material in contactwith each other:

in Formula (1), each of A and B independently represents —NH— or —O—,each of R¹ to R³ independently represents hydrogen an amino group ahydroxy group or a halogen, each of R⁴ to R¹³ independently representshydrogen, an alkyl group, a nitro group or a sulfonic group, Ki^(n+)represents an organic ammonium ion, m represents 1 or 2, and nrepresents 1 or 2; the sulfonic group is —SO₃ or SO₃M, the number of—SO₃ being m, M representing hydrogen or an alkali metal, and each of Mmay be identical or not provided that the number of SO₃M is 2 or more.9. Method of laser welding of claim 8, wherein said polyolefin elastomeris polypropylene elastomer and the laser ray absorbing materialcomprises a laser ray absorbing colored resin composition incorporatingcarbon black and/or another laser absorbing colorant.
 10. Method oflaser welding of claim 8, wherein the laser ray absorbing materialcomprises a laser ray absorbing colored resin composition incorporatingcarbon black and/or another laser absorbing colorant.
 11. Method oflaser welding of claim 8, wherein a contact portion of the laser raytransmitting material and the laser ray absorbing material is welded ina state that satisfies Formula (A):Q=P/(S·φ)>0.4   (A) where Q: amount of heat on surface of laser rayabsorbing material (J/mm²) P: output (W) of laser that laser raytransmitting material transmits S: laser scanning speed (mm/sec) φ: spotdiameter of laser (mm).
 12. Method of laser welding comprising welding aportion of contact of a laser ray transmitting material comprising alaser ray transmitting colored polypropylene resin compositioncontaining an anthraquinone salt forming dye represented by Formula (1)below and a red azo salt forming dye, the polypropylene resincomposition containing 5 to 120% by weight of reinforcing glass fiberrelative to said polypropylene resin, and a laser ray absorbing materialby irradiating laser ray so that the laser ray transmitting materialtransmits the laser ray and the laser ray is absorbed in the laser rayabsorbing material with the laser ray transmitting material and thelaser ray absorbing material in contact with each other:

in Formula (1), each of A and B independently represents —NH— or —O—,each of R¹ to R³ independently represents hydrogen, an amino group, ahydroxy group or a halogen, each of R⁴ to R¹³ independently representshydrogen, an alkyl group, a nitro group or a sulfonic group, Ki^(n+)represents an organic ammonium ion, m represents 1 or 2, and nrepresents 1 or 2; the sulfonic group is —SO₃ or SO₃M, the number of—SO₃ being m, M representing hydrogen or an alkali metal, and each of Mmay be identical or not provided that the number of SO₃M is 2 or more.13. Method of laser welding of claim 12, wherein the laser ray absorbingmaterial comprises a laser ray absorbing colored resin compositionincorporating carbon black and/or another laser absorbing colorant. 14.Method of laser welding of claim 12, wherein the laser ray absorbingmaterial comprises a laser ray absorbing colored resin compositionincorporating carbon black, the primary particle diameter of said carbonblack being 15 to 50 nm.
 15. Method of laser welding of claim 12,wherein a contact portion of the laser ray transmitting material and thelaser ray absorbing material is welded in a state that satisfies Formula(A):Q=P/(S·φ)>0.4   (A) where Q: amount of heat on surface of laser rayabsorbing material (J/mm²) P: output (W) of laser that laser raytransmitting material transmits S: laser scanning speed (mm/sec) φ: spotdiameter of laser (mm).
 16. Method of laser welding comprising welding aportion of contact of a laser ray transmitting material comprising apolyolefin resin composition containing an anthraquinone salt formingdye represented by Formula (1) below and a red azo salt forming dye anda laser ray absorbing material comprising a laser ray absorbing coloredresin composition incorporating carbon black and/or another laserabsorbing colorant in a state that satisfies Formula (A) below byirradiating laser ray so that the laser ray transmits the laser raytransmitting material and is absorbed in the laser ray absorbingmaterial with the laser ray transmitting material and the laser rayabsorbing material in contact with each other:

in Formula (1), each of A and B independently represents —NH— or —O—,each of R¹ to R³ independently represents hydrogen, an amino group, ahydroxy group or a halogen, each of R⁴ to R¹³ independently representshydrogen, an alkyl group, a nitro group or a sulfonic group, Ki^(n+)represents an organic ammonium ion, m represents 1 or 2, and nrepresents 1 or 2; the sulfonic group is —SO₃ or SO₃M, the number of—SO₃ being m, M representing hydrogen or an alkali metal, and each of Mmay be identical or not provided that the number of SO₃M is 2 or more;Q=P/(S·φ)>0.4   (A) where Q: amount of heat on surface of laser rayabsorbing material (J/mm²) P: output (W) of laser that laser raytransmitting material transmits S: laser scanning speed (mm/sec) φ: spotdiameter of laser (mm).
 17. Method of laser welding of claim 16, whereinthe primary particle diameter of said carbon black is 15 to 100 nm. 18.Method of laser welding of claim 17, wherein the BET specific surfacearea of said carbon black is 30 to 500 m²/g.
 19. Laser ray transmittingcolored polyolefin resin composition of claim 1, which contains a yellowcolorant, along with said anthraquinone salt forming dye and red azosalt forming dye.
 20. Method of laser welding of claim 4, wherein saidlaser ray transmitting colored polyolefin resin composition contains ayellow colorant, along with said anthraquinone salt forming dye and redazo salt forming dye.
 21. Laser ray transmitting colored polyolefinresin composition of claim 7, which contains a yellow colorant, alongwith said anthraquinone salt forming dye and red azo salt forming dye.22. Method of laser welding of claim 8, wherein said laser raytransmitting colored polyolefin resin composition contains a yellowcolorant, along with said anthraquinone salt forming dye and red azosalt forming dye.
 23. Method of laser welding of claim 12, wherein saidlaser ray transmitting colored polyolefin resin composition contains ayellow colorant, along with said anthraquinone salt forming dye and redazo salt forming dye.
 24. Method of laser welding of claim 16, whereinsaid polyolefin resin composition contains a yellow colorant, along withsaid anthraquinone salt forming dye and red azo salt forming dye. 25.Laser ray transmitting colored polyolefin resin composition containingan anthraquinone salt forming dye represented by Formula (1) below and ared azo salt forming dye, the polyolefin resin composition containing 10to 60% by weight of reinforcing glass fiber relative to said polyolefinresin, said polyolefin resin being polypropylene resin:

in Formula (1), each of A and B independently represents —NH— or —O—,each of R¹ to R³ independently represents hydrogen, an amino group, ahydroxy group or a halogen, each of R⁴ to R¹³ independently representshydrogen, an alkyl group, a nitro group or a sulfonic group, Ki^(n+)represents an organic ammonium ion, m represents 1 or 2, and nrepresents 1 or 2; the sulfonic group is —SO₃ or SO₃M, the number of—SO₃ being m, M representing hydrogen or an alkali metal, and each of Mmay be identical or not provided that the number of SO₃M is 2 or more.26. Laser ray transmitting colored polyolefin resin composition of claim25, which contains a yellow colorant, along with said anthraquinone saltforming dye and red azo salt forming dye.
 27. A use of an anthraquinonesalt forming dye represented by Formula (1) below as a laser raytransmitting colorant for polyolefin resin composition containing 5 to50% by weight of talc relative to said polyolefin resin:

in Formula (1), each of A and B independently represents —NH— or —O—,each of R¹ to R³ independently represents hydrogen, an amino group, ahydroxy group or a halogen, each of R⁴ to R¹³ independently representshydrogen, an alkyl group, a nitro group or a sulfonic group, Ki^(n+)represents an organic ammonium ion, m represents 1 or 2, and nrepresents 1 or 2; the sulfonic group is —SO₃ or SO₃M, the number of—SO₃ being m, M representing hydrogen or an alkali metal, and each of Mmay be identical or not provided that the number of SO₃M is 2 or more.28. A use of an anthraquinone salt forming dye represented by Formula(1) below as a laser ray transmitting colorant for polyolefin resincomposition, said polyolefin resin being a polyolefin elastomer:

in Formula (1), each of A and B independently represents —NH— or —O—,each of R¹ to R³ independently represents hydrogen, an amino group, ahydroxy group or a halogen, each of R⁴ to R¹³ independently representshydrogen, an alkyl group, a nitro group or a sulfonic group, Ki^(n+)represents an organic ammonium ion, m represents 1 or 2, and nrepresents 1 or 2; the sulfonic group is —SO₃ or SO₃M, the number of—SO₃ being m, M representing hydrogen or an alkali metal, and each of Mmay be identical or not provided that the number of SO₃M is 2 or more.29. A use of an anthraquinone salt forming dye represented by Formula(1) below as a laser ray transmitting colorant for polyolefin resincomposition containing 10 to 60% by weight of reinforcing glass fiberrelative to said polyolefin resin, said polyolefin resin beingpolypropylene resin:

in Formula (1), each of A and B independently represents —NH— or —O—,each of R¹ to R³ independently represents hydrogen, an amino group, ahydroxy group or a halogen, each of R⁴ to R¹³ independently representshydrogen, an alkyl group, a nitro group or a sulfonic group, Ki^(n+)represents an organic ammonium ion, m represents 1 or 2, and nrepresents 1 or 2; the sulfonic group is —SO₃ or SO₃M, the number of—SO₃ being m, M representing hydrogen or an alkali metal, and each of Mmay be identical or not provided that the number of SO₃M is 2 or more.